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- //=======================================================================
- // Copyright 2002 Indiana University.
- // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
- //
- // Distributed under the Boost Software License, Version 1.0. (See
- // accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- //=======================================================================
- #ifndef BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP
- #define BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP
- #include <boost/graph/topological_sort.hpp>
- #include <boost/graph/dijkstra_shortest_paths.hpp>
- // single-source shortest paths for a Directed Acyclic Graph (DAG)
- namespace boost {
- // Initalize distances and call depth first search
- template <class VertexListGraph, class DijkstraVisitor,
- class DistanceMap, class WeightMap, class ColorMap,
- class PredecessorMap,
- class Compare, class Combine,
- class DistInf, class DistZero>
- inline void
- dag_shortest_paths
- (const VertexListGraph& g,
- typename graph_traits<VertexListGraph>::vertex_descriptor s,
- DistanceMap distance, WeightMap weight, ColorMap color,
- PredecessorMap pred,
- DijkstraVisitor vis, Compare compare, Combine combine,
- DistInf inf, DistZero zero)
- {
- typedef typename graph_traits<VertexListGraph>::vertex_descriptor Vertex;
- std::vector<Vertex> rev_topo_order;
- rev_topo_order.reserve(num_vertices(g));
- // Call 'depth_first_visit', not 'topological_sort', because we don't
- // want to traverse the entire graph, only vertices reachable from 's',
- // and 'topological_sort' will traverse everything. The logic below
- // is the same as for 'topological_sort', only we call 'depth_first_visit'
- // and 'topological_sort' calls 'depth_first_search'.
- topo_sort_visitor<std::back_insert_iterator<std::vector<Vertex> > >
- topo_visitor(std::back_inserter(rev_topo_order));
- depth_first_visit(g, s, topo_visitor, color);
- typename graph_traits<VertexListGraph>::vertex_iterator ui, ui_end;
- for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui) {
- put(distance, *ui, inf);
- put(pred, *ui, *ui);
- }
- put(distance, s, zero);
- vis.discover_vertex(s, g);
- typename std::vector<Vertex>::reverse_iterator i;
- for (i = rev_topo_order.rbegin(); i != rev_topo_order.rend(); ++i) {
- Vertex u = *i;
- vis.examine_vertex(u, g);
- typename graph_traits<VertexListGraph>::out_edge_iterator e, e_end;
- for (boost::tie(e, e_end) = out_edges(u, g); e != e_end; ++e) {
- vis.discover_vertex(target(*e, g), g);
- bool decreased = relax(*e, g, weight, pred, distance,
- combine, compare);
- if (decreased)
- vis.edge_relaxed(*e, g);
- else
- vis.edge_not_relaxed(*e, g);
- }
- vis.finish_vertex(u, g);
- }
- }
- namespace detail {
- // Defaults are the same as Dijkstra's algorithm
- // Handle Distance Compare, Combine, Inf and Zero defaults
- template <class VertexListGraph, class DijkstraVisitor,
- class DistanceMap, class WeightMap, class ColorMap,
- class IndexMap, class Params>
- inline void
- dag_sp_dispatch2
- (const VertexListGraph& g,
- typename graph_traits<VertexListGraph>::vertex_descriptor s,
- DistanceMap distance, WeightMap weight, ColorMap color, IndexMap /*id*/,
- DijkstraVisitor vis, const Params& params)
- {
- typedef typename property_traits<DistanceMap>::value_type D;
- dummy_property_map p_map;
- D inf =
- choose_param(get_param(params, distance_inf_t()),
- (std::numeric_limits<D>::max)());
- dag_shortest_paths
- (g, s, distance, weight, color,
- choose_param(get_param(params, vertex_predecessor), p_map),
- vis,
- choose_param(get_param(params, distance_compare_t()), std::less<D>()),
- choose_param(get_param(params, distance_combine_t()), closed_plus<D>(inf)),
- inf,
- choose_param(get_param(params, distance_zero_t()),
- D()));
- }
- // Handle DistanceMap and ColorMap defaults
- template <class VertexListGraph, class DijkstraVisitor,
- class DistanceMap, class WeightMap, class ColorMap,
- class IndexMap, class Params>
- inline void
- dag_sp_dispatch1
- (const VertexListGraph& g,
- typename graph_traits<VertexListGraph>::vertex_descriptor s,
- DistanceMap distance, WeightMap weight, ColorMap color, IndexMap id,
- DijkstraVisitor vis, const Params& params)
- {
- typedef typename property_traits<WeightMap>::value_type T;
- typename std::vector<T>::size_type n;
- n = is_default_param(distance) ? num_vertices(g) : 1;
- std::vector<T> distance_map(n);
- n = is_default_param(color) ? num_vertices(g) : 1;
- std::vector<default_color_type> color_map(n);
- dag_sp_dispatch2
- (g, s,
- choose_param(distance,
- make_iterator_property_map(distance_map.begin(), id,
- distance_map[0])),
- weight,
- choose_param(color,
- make_iterator_property_map(color_map.begin(), id,
- color_map[0])),
- id, vis, params);
- }
-
- } // namespace detail
-
- template <class VertexListGraph, class Param, class Tag, class Rest>
- inline void
- dag_shortest_paths
- (const VertexListGraph& g,
- typename graph_traits<VertexListGraph>::vertex_descriptor s,
- const bgl_named_params<Param,Tag,Rest>& params)
- {
- // assert that the graph is directed...
- null_visitor null_vis;
- detail::dag_sp_dispatch1
- (g, s,
- get_param(params, vertex_distance),
- choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
- get_param(params, vertex_color),
- choose_const_pmap(get_param(params, vertex_index), g, vertex_index),
- choose_param(get_param(params, graph_visitor),
- make_dijkstra_visitor(null_vis)),
- params);
- }
-
- } // namespace boost
- #endif // BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP
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